This invention relates to newly identified polynucleotides, polypeptides encoded by them and to the use of such polynucleotides and polypeptides, and to their production. More particularly, the polynucleotides and polypeptides of the present invention relate to Interleukin-1 family, hereinafter referred to as IL-1ra beta. The invention also relates to inhibiting or activating the action of such polynucleotides and polypeptides.
Interleukin 1 refers to two proteins (IL1xcex1 and IL1xcex2) which play a key role early in the inflammatory response [for a review see C. A. Dinarello, Blood, 87:2095-2147 (1996) and references therein]. Both proteins are made as 31 kDal intracellular precursor proteins which are cleaved upon secretion to yield mature carboxy-terminal 17 kDal fragments which are biologically active. In the case of IL-1xcex2, this cleavage involves an intracellular cysteine protease, known as ICE, which is required to release the active fragment from the inactive precursor. The precursor of IL-1xcex1 is active.
These two proteins act by binding to cell surface receptors found on almost all cell types and triggering a range of responses either alone or in concert with other secreted factors. These range from effects on proliferation (eg of fibroblasts, T cells), apoptosis (eg A375 melanoma cells), cytokine induction (eg of TNF, IL, IL8), receptor activation (eg E-selectin), eicosanoid production (eg PGE2) and the secretion of degradative enzymes (eg collagenase). To achieve this, IL-1 activates transcription factors such as NF-xcexaB and AP-1, Several of the activities of IL-1 action on target cells are believed to be mediated through activation of kinase cascades that have also been associated with cellular stresses, such as the stress activated MAP kinases JNK/SAPK and p38.
A third member of the IL-1 family was subsequently discovered which acts as a natural antagonist of IL-1xcex1 and IL-1xcex2 by binding to the IL-1 receptor but not transducing an intracellular signal or a biological response. The protein was called IL-1ra (for IL-1 receptor antagonist) or IRAP (for IL-1 receptor antagonist protein). At least three alternatively splice forms of IL-1ra exist: one encodes a secreted protein, and the other two encode intracellular proteins. The relative role of the three forms and reason for their different localization is not known. All three proteins, IL-1xcex1, IL-1xcex2 and IL-1ra share approximately 25-30% amino acid identity and a similar three-dimensional structure consisting of twelve xcex2-strands folded into a xcex2-barrel, with an internal thrice repeated structural motif.
There are three known IL-1 receptor subunits. The active receptor complex consists of the type I receptor and IL1RAcP (for IL-1 accessory protein). The type I receptor is responsible for binding of the three ligands, and is able to do so in the absence of the IL1RAcP. However signal transduction requires interaction of IL-1xcex1 or xcex2 with the IL1RAcP. IL-1ra does not interact with the IL-1RAcP and hence cannot signal. A third receptor subunit, the type II receptor, binds IL-1xcex1 and IL-1xcex2 but cannot signal due to its lack of an intracellular domain. Rather it act as a decoy either in its membrane form or an antagonist in a cleaved secreted form, and hence inhibits IL-1 activity. It only weakly binds IL-1ra.
Many studies using IL-1ra, soluble IL-1R, derived from the extracellular domain of the type I IL-1R, antibodies to IL-1xcex1 or xcex2 and transgenic knockouts of these genes have shown conclusively that the IL-1s play a key role in a number of pathophysiologies (see C. A. Dinarello, Blood 87:2095-2147 (1996) for a review). For example, IL-1ra has been shown to be effective in animal models of septic shock, rheumatoid arthritis, graft versus host disease, stroke, cardiac ischemia, and is currently in clinical trials for some of these indications. Moreover, IL-1xcex1 and xcex2 have shown some potential as hematopoietic stem cell stimulators with potential as radio- and chemoprotectants.
More recently, a more distant member of the IL-1 family was identified. This protein, originally isolated through its ability to induce Interferon gamma in T cells and hence called Interferon gamma inducing factor (IGIF) [H. Okamura et al., Nature 378:88-91 (1995)], was subsequently shown to fold in a similar structure to the IL-1s and share weak amino acid identity [Bazan et al., Nature 379:591 (1996)]. The name IL-1xcex3 was proposed. IGIF appears to play a direct role in the liver damage which occurs during toxic shock and is therefore like the other IL-1s in playing an early role in inflammatory and stressful conditions.
This indicates that these Interleukin-1s have an established, proven history as therapeutic targets. Clearly there is a need for identification and characterization of further members of Interleukin-1 family which can play a role in preventing, ameliorating or correcting dysfunctions or diseases, including, but not limited to, chronic and acute inflammation, septicemia, shock, arthritis, inflammatory bowel disease, graft vs. host disease, autoimmunity, stroke, cardiac ischemia, acute respiratory disease syndrome (ARDS), psoriasis, restenosis, traumatic brain injury, AIDS, cachexia, allergy, parasite infection, allergic rhinitis, allergic asthma, atopic dermatitis, allergic inflammatory diseases, and delayed hypersensitivity.
In one aspect, the invention relates to IL-1ra beta polypeptides and recombinant materials and methods for their production. Another aspect of the invention relates to methods for using such IL-1ra beta polypeptides and polynucleotides. Such uses include the treatment of chronic and acute inflammation, septicemia, arthritis, inflammatory bowel disease, graft vs. host disease, autoimmunity, stroke, shock, cardiac ischemia, acute respiratory disease syndrome (ARDS), psoriasis, restenosis, traumatic brain injury, AIDS, cachexia, allergy, parasite infection, allergic rhinitis, allergic asthma, atopic dermatitis, allergic inflammatory diseases, and delayed hypersensitivity,, among others. In still another aspect, the invention relates to methods to identify agonists and antagonists using the materials provided by the invention, and treating conditions associated with IL-1ra beta imbalance with the identified compounds. Yet another aspect of the invention relates to diagnostic assays for detecting diseases associated with inappropriate IL-1ra beta activity or levels.